The B-52G aircraft is a heavy bomber equipped with six crew stations.
Each crew station has its escape hatch and ejection seat. This unit
contains a description of the various components that make up the
B-52G egress systems. These systems include the upward ejection system,
downward ejection system, and their respective escape hatches.

In this section, we will discuss the escape hatches and some of the
components that make up the emergency escape system on the B-52 aircraft.
We will begin with a discussion of the pilot and copilot hatches then move
on to electronic warfare officer, gunner, navigator, and the radar
navigator hatches. We will conclude this section with a look at a
few of the components that make up the egress system.

Each crew station has an independent ejection system that must be
initiated by the crewmember. The ejection systems include an escape
hatch for each ejection seat. In figure 1, you see the seat and
hatch arrangement. The upper hatches have both inside and outside
manual handles, while the downward hatches have only inside handles.
The handles unlock, open and close the hatch. The hatch is jettisoned
during the seat ejection sequence. Let's begin with a look at the
pilot and copilot hatches.

Figure 2. Pilot and Copilot Escape Hatches.

Pilot and copilot escape hatches.
The pilot and copilot escape hatches are
situated directly above their ejection seats and the mechanism for each
is identical (fig. 2). The hatches serve a dual purpose because they
provide an opening for emergency seat ejection as well as a means of
ground entry or exit to or from the forward crew compartment after
ditching or crash landing. Opening of the hatches may be accomplished
by three methods: an outside handle, an inside handle, and a thruster
mechanism for jettisoning during ejection. If a hatch is opened using
the inside handle, it must be closed using the same handle. This is
because the handles completely disengage from the torque tubes as the
hatch moves to the fully CLOSED and LOCKED position.

The hatches are hinged at the aft end with hinges that disengage when
the hatches are swung open. Two jack arms at the front end and six
latch hooks (three on each side) close and lock the hatch. These jack
arms and latch hooks are connected to two torque tubes that run the
length of the hatch. The torque tubes rotate in reverse of each other
to close and lock the hatch. When the torque tubes are rotated, the
jack arms, which are guided by tracks on the forward hatch well opening,
draw the hatch closed and at the same time actuate the latches that
extend outward to engage the latch arms. The inside and outside
handles and the hatch jettison thruster are connected to the torque
tubes.

Figure 3. EWO and Gunner Escape Hatches.

Electronic warfare officer (EWO) and gunner escape hatches.
The EWO
and gunner escape hatches (fig. 3) are similar to the pilot and
copilot hatches in design and operation except that a lifter mechanism
has been incorporated in the jettison mechanism. This mechanism assists
in jettisoning the hatch when the hatch jettison thruster is fired. The
lifter mechanism consists of a lifter, jettison assist straps, and a
pushoff mechanism. The lifter is a door that rests on the outside of
the hatch and is hinged at the aft end. It is held against the hatch
by pushrods on the forward end. When the hatch is in the normal position,
the pushrod arms engage a ball on the ends of the pushrods. The lifter
mechanism is held in the normal position by the thruster. When the
thruster is fired, the lifter
torque shaft rotates causing the pushrod arms to rotate, pushing the
pushrods outboard. At the fully rotated position, the pushrods disengage
from the pushrod arms, allowing the lifter to swing free in the airstream.
Jettison assist straps attached to the hatch and to the lifter stop the
lifter after it has swung away from the hatch 30°. These straps absorb
the shock of extending the lifter and transfer the air load from the
lifter to the hatch to assist in jettisoning the hatch.

Figure 4. Navigator and Radar Navigator Escape
Hatches.

Navigator and radar navigator escape hatches.
In figure 1, you see that
the navigator and radar navigator escape hatches are located directly
below the downward ejection seats. The hatches (fig. 4) are closed
normally; their main purpose is to provide an opening for the downward
ejection seats during an emergency. An emergency escape hatch jettison
handle, which is located in the forward inboard corner of the escape
hatch well, provides an alternate means of jettisoning the escape hatch
for bailout if the normal system fails to operate. When jettisoning
takes place, gas pressure from the arming initiator fires the hatch
jettison thruster. Gas expansion in the thruster causes the thruster
shaft to extend. The thruster shaft is connected to the torque tube
by a thruster extension and the actuator arm (fig. 5). One side of
the thruster extension contacts a lug on the lock cam. The thruster
extension is slotted so that as the thruster shaft. extends, the
thruster extension first rotates the lock cam. When the lock cam
has rotated far enough to unlock the mechanism, the thruster extension
picks up the pin through the actuator arm causing it to rotate. A lug
on the actuator arm bears against the lock arm causing the torque
tubes to rotate and open the forward end of the hatch into the
slipstream where the hatch is carried free of the aircraft. A
hydraulic damper is incorporated in the mechanism in such a manner
that the shock produced by the thruster is reduced. Also, a lifter
mechanism assists in jettisoning the hatch when the hatch jettison
thruster is fired. The jettison assist straps stop the lifter after
it has swung approximately 25° away from the hatch.

Figure 5. Thruster Extention and Actuator Arm.

Escape hatch warning system.
The hatch warning system is a 24-volt DC
electrical warning system that receives power from the pilot auxiliary
circuit breaker panel. All six escape hatches are included in the
system. The forward entry door and rear access door are connected
also to this circuit. The power circuit is so arranged that an amber
warning light on the pilot instrument panel comes on when one or more
of the hatches are open.

Each escape hatch is equipped with a microswitch that is part of the
hatch warning circuit. These switches are spring-loaded to the closed
position and close the circuit to the pilot instrument panel warning
light that comes on when any hatch is not closed and locked. The switch
is actuated by the lockpin in the escape hatch locking mechanism. The
hatch position warning circuit informs the pilot and copilot of a hatch
that is not closed and locked.

Now let's take a look at some of the components that make up the escape
system. This listing is not intended to be all inclusive. It only
covers those areas that are unique to the B-52.

Thrusters. A thruster is a device that derives its energy from an
explosive cartridge contained within the unit. When ballistic gas
pressure is applied to the inlet port, the firing pin shear pin is
sheared and the firing pin is propelled against the cartridge. As
the cartridge fires, the burning propellant produces ballistic gas
pressure that moves an integral piston and imparts a thrust to an
attached load.

Control column stowage thruster.
The control column stowage thruster
is a cartridge-actuated device that releases the stowage spring to
move the control column forward so that it will not interfere with
the seat ejections Two of these thrusters are used in the aircraft
one for the pilot ejection system and one for the copilot system. The
pilot control column stowage thruster is located in the control column
disconnect mechanism below the pilot side panel. The copilot control
column stowage thruster is located under the copilot side panel.

Fire control support stowage thruster.
The gunner's fire control support
stowage thruster is a cartridge-actuated device that stows the gunner
fire control support during the seat ejection sequence. The thruster is
located aft of the gunner's instrumenent panel.

Figure 6. Table Storage Thrusters.

When the thruster is fired, the latching mechanism that holds the fire
control support in the extended position is released, allowing the
thruster to pull the support to the stowed position.

Table stowage thrusters.
The radar navigator and navigator use table
stowage thrusters (fig. 6) to stow their work tables automatically
during the seat ejection sequence. The thrusters are located below
the instrument panel and between the two tables. Each thruster is
gas fired by a table stowage thruster initiator which is fired by
gas expansion from the arming initiator. Slip joints on the aft end
of the thrusters allow the tables to be stowed manually by pushing
them forward.

Leg guard thruster.
The downward ejection seats leg guards are rotated
by a thruster attached to the bottom of the seat bucket and to a
linkage attached to the leg guard torque robe. The thruster is fired
by gas expansion from the arming initiator. The force of the thruster
acts on the leg guard torque tube, rotating the leg guards to the
ejection position.

Catapults. The ejection seat catapult is a three-tube telescoping
ejection mechanism powered by an explosive charge. The catapult is
made up of an outer tube, an intermediate tube, and an inner tube
that contains the explosive charge. The inner tube has a trunnion
which attaches to the ejectable rails and the outer tube has a trunion
which attaches to the fixed seat rails. The intermediate tube serves
to increase the effective stroke of the catapult and thus cushion the
acceleration force. The catapult is fired by an initiator in the
ejection system
after the proper sequence of events has taken place. Upon ignition
of the explosive charge, the catapult extends and ejects the attached
seat.

Man-seat separation system. The EWO, gunner, navigator, and radar
navigator ejection seats are provided with a man-seat separation
system that provides positive separation of crewmembers after ejection
from the aircraft. The system consists of a reel-type ballistic
actuator, jackshaft, and a harness made of two nylon straps. The harness
is installed in the seat under the global survival kit and parachute. The
lower end of the harness is attached to the forward side of the seat bucket
and the upper end is attached to the jackshaft on the back side of the
seat. The jackshaft is driven by the ballistic actuator which is
connected by ballistic tubing to the man-seat separation booster
initiator. The booster initiator is connected to both integrated
harness release initiators. When either integrated harness release
initiator is fired releasing the integrated harness, gas pressure
from the initiator also fires the man-seat separation booster initiator
that in turn fires the cartridge in the actuator. After the integrated
harness is released, the actuator rotates the jackshaft pulling the
harness tight forming one side of a triangle, the other two sides form
the seat bottom and seat back. As the man-seat separation harness is
pulled tight, the harness throws the occupant clear of the seat.

Man-seat separation (rotary) actuator.
Rotary actuators are ballistic
gas pressure-actuated devices designed to forcibly separate the crewmember
from the seat after ejection. When gas pressure is applied to the inlet
port of the actuator, the firing pin is propelled against the cartridge.
As the cartridge fires, the resulting gas pressure exerts force on the
bottom of the ballscrew. Linear motion of the ballscrew causes the ballnut
to rotate and wind in the webbing. As the webbing becomes taut, the
crewmember is forced from the seat.

Integrated harness attachment fittings.
Each of the upward ejection seats
has three integrated harness attachment fittings. Two of the attachment
fittings, one on each side of the seat bucket, hold the lap belts in
place, and the third, just below the headrest, attaches the upper
restraint to the inertia reel. The integrated harness release handle,
which is located on the left side of the seat bucket, is used to manually
unlock the attachment fittings. The integrated harness release pin-pull
cylinder is operated by gas pressure and is located on the back of the
seat bucket. This cylinder automatically releases the attachment fittings
during seat ejection. The integrated harness pin-pull cylinder receives
the gas pressure from two sources:

(1) The integrated harness release 0.30-second delay initiator that is
initiated when the catapult is fired.

(2) The integrated harness zero delay initiator that is mechanically
tripped as the ejection seat leaves the intermediate rails.

The 0.30-delay initiator is an automatic backup in the event the zero
delay fails to fire.

Each attachment fitting consists of a slotted fitting and a bellcrank-type
hook. When the end fitting of the harness is inserted in the slot, the hook
rotates into a hole in the harness end fitting. A locking device then locks
the hook in this position, attaching the harness to the attachment fitting.
Pulling up on the harness release handle unlocks the attachment hooks and
allows the harness fittings to pull free. Also, the left attachment fitting
is equipped with a receptacle for attaching the personnel parachute
lanyard, called the gold key, to the seat. Attaching the parachute
lanyard or gold key to the seat results in automatic parachute
deployment upon person-seat separation.

Ankle restraints.
The downward ejection seats are equipped with ankle
restraints that hold the occupant's ankles in place during the ejection
sequence. The restraints are located on the lower forward part of the
seat in such a position that the ankle restraint triggers behind each
ankle cause the restraints to rotate around the ankles when touched
by the legs. This action must be accomplished before pulling the ejection
control handle. In their final deployed position, the restraints can
rotate out but not upward. If for any reason it is decided not to complete
the ejection sequence, the ankle restraints may be restored to the stowed
position by rotating the ankle restraints out and down from the seat.
The ankle restraints rotate to their deployed position any time the
ankle restraint triggers are depressed.

Drogue parachute.
The upward ejection seats are equipped with a drogue
parachute that deploys immediately after the seat departs the aircraft.
The deployed parachute stabilizes and decelerates the ejection seat to
assist in the positive separation of the seat occupant.

On pilot and copilot seats, the drogue parachute pack is supported above
the headrest by tubular arms that are attached to the ejectable rails.
The parachute support is held in position by a latch assembly that is
actuated by a pin-pull cylinder. During the seat ejection sequence,
the ballistically actuated pin-pull cylinder releases the spring-loaded
parachute support that extends and rotates away from the seat as the
seat moves up the rails and departs the aircraft. The parachute support
arms rotate aft and lock in trail position at the limit of the
restraining straps. The drogue parachute ripcord is pulled to deploy
the parachute as the support rotates to the trail position.

On EWO and gunner seats, the drogue parachute pack is stowed between
the drag panel and underside of the seat bucket. The pack is attached
to the seat bucket by a latch mechanism. As the arming levers are
rotated up, the drag panel is released and allowed to drop down.
During initial ejection from the aircraft, gravity and catapult induced
acceleration cause the drag panel to rotate downward to the limit of
the restraint cables. The sliding plate extends from the drag panel and
pulls the parachute bridle lines from their stowage pouches. As the
seat and ejectable rails are unlatched from the intermediate rails and
continue their upward travel, the static line, which is attached to
the intermediate rails, releases the latch securing the drogue parachute
to the bottom of the seat bucket. The drogue parachute is pulled
away from the seat by the static line until the bridle lines become
taut. At this point, the static line pulls the parachute pack away from
the parachute and deployment of the parachute is accomplished.

In this section we will take a look at the ejection systems. We will
start with a description of the upward system. Then we will move on
to the upward ejection seats. Next we will discuss the sequence of
events during an ejection. Once we have finished with the upward system,
we will move on to the downward system.

The upward ejection system provides emergency escape provisions for the
pilot, copilot, electronic warfare officer (EWO), and gunner by upward
ejection of their seats. Each seat has its own ejection system consisting
of the seat and the escape hatch, which is located directly overhead.
There are no connections between the ejection systems, therefore, each
crewmember must initiate ejection individually. Operation, once initiated,
is fully automatic. Operation of the seats is similar except that the
EWO and gunner seats face aft and contain no control column stowage
facilities. The gunner fire control support is stowed automatically and
in the same manner as the pilot and copilot control columns. Ejection of
the seats and escape hatches is initiated by a series of ballistic
devices and linkages incorporated in the seat. Each seat is the catapult
type equipped with arming levers and triggers.

Figure 7. Upward Ejection Seat.

Upward ejection seat description.
In figure 7, you see that the upward
ejection seats are bucket-type seats located under the upward ejection
escape hatches. A seat consists of the seat bucket (item 1 ), three seat
positioning actuators (item 2), the ejectable rails (item 3), the fixed
rails (item 4), and telescoping intermediate rails (item 5). The seat
bucket is equipped with an inertia reel, a survival kit (item 6),
adjustable armrests (item 7), headrest (item 8), catapult trigger (item 9),
unlocking lever (item 10), arming lever (item 11 ), leg support (or drag
panel on EWO and gunner seats) (item 12), provisions for use of an
integrated harness, and a drogue parachute (item 13). The pilot and copilot
seats are provided also with a drogue parachute support (item 14) that
aids in deployment of the parachute. The seat is provided with a personnel
parachute (item 15) and a manual opening safety belt (item 16). The
armrests on each side of the seat are adjustable up and down to allow
freedom of movement of the occupant and easy access to the seat. The
ejection controls are located on the forward end of the armrests. They
consist of the unlocking lever, a loop-type arming lever, and the
catapult firing trigger. The controls have a dual capability; that
is, either right or left hand controls will arm the seat and fire
the catapult. Three attaching fittings (item 17) are provided for use
of the integrated harness, one located on each side of the seat bucket
and one just below the headrest. The leg support (or drag panel), is
hinged on the lower forward edge of the seat bucket in such a manner
that it can be folded back when not in use and is automatically extended
when the seat is armed. The seat bucket is attached to the ejectable
rails by three seat positioning actuators which allow the seat bucket
to be adjusted up and down, fore and aft, and tilted. The telescoping
intermediate rails and the fixed rails guide the ejectable rails and
seat upward when ejected from the aircraft. All tube runs in the upward
ejection system are made up of sections of plastic metal-armored
flexible tube.

Operation.
Ejection of the seats and escape hatches is initiated by a
series of ballistic devices and linkages incorporated in the seat. Each
seat is the catapult type equipped with arming levers and triggers.

When the arming levers are rotated to the up position, the pilot or
copilot control column or gunner fire control support is stowed, the
shoulder harness is locked, the hatch is jettisoned, and the ejection
seat is armed. On pilot and copilot seats, the leg support is released
also and the drogue parachute support is unlatched and extends upward.
On EWO and gunner seats, the drag panel located under the seat releases
and drops down. The occupant must still pull the trigger located on either
the right or left armrest before the catapult is fired and ejection
occurs. As the catapult is fired, a time-delay initiator is
ballistically fired, also. This delay initiator, together with
a zero delay initiator that is mechanically tripped as the ejection
seat leaves the intermediate rails, releases the occupant from the
seat after it has cleared the aircraft. Also, as the pilot or copilot
ejection seat leaves the aircraft, the drogue parachute support rotates
away from the seat and the drogue parachute is deployed. As the EWO or
gunner seat accelerates up the rails, the drag panel rotates downward
and the drogue parachute is deployed as the seat leaves the aircraft.
A man-seat separation system is provided also on the EWO and gunner
seats to give positive separation of the seat occupant after ejection
from the aircraft.

The hatches are equipped with inside and outside handles for manual
operation. Each hatch is provided with a warning switch that causes
an amber light on the pilot instrument panel to come on when the
hatch is not closed and locked properly.

Figure 8. Pilot and Copilot Ejection Sequence.

Pilot and copilot ejection sequence.
The upward ejection systems are
basically the same. The hatches are jettisoned when the arming levers
are rotated, and the seats eject when the triggers are squeezed.
Refer to figure 8 as we discuss the ejection sequence.

To begin the ejection sequence, raise both armrests to the up position
and rotate either or both arming levers. The arming levers are
interconnected, therefore, rotating one will rotate the other.

Rotating the arming levers fires an M3 arming initiator, locks the
inertia reel, releases the leg support, and exposes the left or right
trigger. Gas pressure from the M3A2 arming initiator fires the M5A2
hatch jettison booster initiator and control column stowage thruster
which stows the control column. Gas pressure from the M5A2 booster
initiator fires the M1A2 hatch jettison thruster, which, in turn,
jettisons the hatch. As the hatch is jettisoned, the M3A2 catapult
safety pin-pull initiator is fired by means of a telescoping linkage.

Gas expansion from the catapult safety pin-pull initiator operates the
catapult safety pin-pull cylinder and fires the drogue parachute
support arm release initiator. Operation of the catapult safety
pin-pull cylinder retracts the safety pin from the M3A2 catapult
initiator, thus arming seat. If the catapult safety pin-pull initiator
fails to fire when the hatch is jettisoned, pulling the manual safety
pin-pull lever operates the safety pin-pull cylinder manually. Gas
expansion from the drogue parachute support arm release initiator
operates the drogue parachute support arm release pin-pull cylinder
retracting latch mechanism that allows the support arms to extend and
rotate away from the seat. The parachute support will not rotate away
from the seat until the seat is ejected.

The next action that the crewmember must take is to squeeze the left
or right trigger. The motion of the trigger linkage fires the catapult
initiator sending gas presswe to fire the M3A1 catapult and the
0.30-second delay M26 integrated harness release delay initiator.
Firing of the catapult causes the seat, ejectable rails, and
intermediate rails to move up the fixed rails.

The drogue parachute support moves away from the seat as the seat
moves upward through the hatch opening. As the parachute support
moves away from the seat, the drogue parachute lanyard is pulled
from the drogue parachute pack thus allowing the pack to be mined
inside out by spring force resulting in parachute deployment. The
drogue parachute support rotates away from the seat until the
restraint straps become taut.

As the latch mechanisms in the ejectable rails move past the top of
the fixed rails, the latches are tripped thus disengaging the
ejectable rails from the intermediate rails. The intermediate rails
contact the snubbers mounted on the fixed rails which prevent the
intermediate rails from moving upward with the seat and ejectable
rails.

As the seat and ejectable rails continue to move upward on the
intermediate rails, the integrated harness release zero delay
initiator is fired by means of a trip attached to the intermediate
rails.

EWO and gunner ejection sequence.
To begin the ejection sequence on
the EWO and gunner seats, lift both armrests to the up position and
rotate either or both arming levers. These arming levers are
interconnected, therefore, rotating one will rotate the other. Refer
to figure 9 as we discuss the EWO and Gunner ejection sequence.

(1) Rotating the arming lever fires the M3A2 arming initiator, locks
the shoulder harness inertia reel, releases the drag panel, and exposes
the right or left trigger. Gas expansion from the arming initiator
fires the M5A2 hatch jettison booster initiator which sends gas
pressure to fire the M1A2 hatch jettison thruster, thus jettisoning
the hatch. On the gunner seat, the gas expansion from the hatch
jettison booster initiator also fires the M3A3 fire control support
stowage thruster that, in turn, stows the fire control support.
As the hatch is jettisoned, the catapult M3A2 safety pin-pull initiator
is fired by means of a telescoping linkage. Gas expansion from the
catapult safety pin-pull initiator operates the catapult safety pin-pull
cylinder that retracts the safety pin from the M3A2 catapult initiator
thus arming the seat. The catapult safety pin-pull cylinder can be
operated manually by pulling the manual safety pin-pull lever.

(2) Again, the crewmember's next action is to squeeze the left or right
trigger. The motion of the trigger linkage fires the catapult initiator
that fires the catapult. and the 0.30-second delay integrated harness
release delay initiator.

Firing of the catapult causes the seat, ejectable rails, and intermediate
rails to move up the fixed rails. As the seat moves upward, the hinged
drag panel rotates downwin:d, the sliding panel extends from the drag
panel, and the drogue parachute bridle lines are pulled from their
stowage containers. The drag panel and sliding panel rotate downward
until the restraint cables become taut.

As the latch mechanisms in the ejectable rails move past the top of
the fixed rails, the latches are tripped thus disengaging the ejectable
rails from the intermediate rails. The intermediate rails contact the
snubbers mounted on the fixed rails and this prevents the intermediate
rails from moving upward with the seat and ejectable rails.

As the seat and ejectable rails continue to move upward on the
intermediate rails, the drogue parachute lanyard (attached to
intermediate rails) becomes taut. The lanyard then releases a latch
that attaches the drogue parachute pack to the bottom of the seat.
When the bridle lines become taut, the parachute lanyard pulls the
parachute pack away from the drogue parachute thus deploying the
parachute.

As the seat and ejectable rails move further up on the intermediate
rails, the integrated harness release M27 zero delay initiator is
fired by means of a trip attached to the intermediate rails.

The downward ejection system provides emergency escape provisions for
the navigator and radar navigator by downward ejection of their seats.
It is composed of forward facing, downward ejection seats, and the
respective escape hatches. Each seat has its ejection system consisting
principally of the seat and the hatch immediately underneath. There is
no connection between the ejection systems of the seats. Control over
the ejection sequence is integral and initiative rests with the individual
occupant. Once ejection is initiated, all events are automatic.

Figure 10. Downward Ejection Seats.

Downward ejection seat description.
In figure 10, you see that the
seats are bucket-type and roller-mounted on fixed ejection rails that
allow downward ejection of the seat and occupant. The downward ejection
system is provided with single motion ejection seats that require the
crewmembers to perform only one operation to complete the ejection
sequence. The ejection control handle, located between the occupant's
legs, initiates a series of ballistic devices and mechanical linkages
incorporated in the seat.

The seat may be adjusted for crew comfort by three electrically
controlled actuators that move the seat horizontally or vertically
or tilt the seat fore and aft. The ejection controls consist of the
leg guards and an ejection control handle located on the forward
edge of the seat between the occupant's legs. A safety pin-pull
handle provides the occupant with a means of manually arming the
catapult initiator in case the catapult safety pin-pull cylinder
does not operate during normal ejection procedure. The initiators
and the pin-pull cylinder are connected by plastic, metal armored,
flexible tubing. The ejection seats are equipped with a drogue
parachute that deploys immediately after the seat departs the aircraft.
The deployed parachute stabilizes and decelerates the ejection seat to
assist in the positive separation of the seat occupant. The drogue
parachute pack is supported below the seat by tubular arms which are
attached to the seat back. The parachute support is held in position
by a pin-pull cylinder. During the seat ejection sequence, the
ballistically actuated pin-pull releases the spring-loaded parachute
support and as the seat moves down the rails and departs the aircraft,
the parachute support arms rotate aft and lock in trail position at the
limit of the restraining straps. The drogue parachute ripcord is pulled
to deploy the parachute as the support rotates to the trail position.
Backup operation of the drogue parachute support release pin-pull
cylinder is provided from the integrated harness release 0.3-second
delay initiator.

Figure 11. Navigator, Radar Navigator Ejection Sequence.

Ejection sequence.
To begin the ejection sequence on the downward seats,
the crewmember must pull the ejection control handle (fig. 11). The
first part of the control handle travel fires the 1Vi~31A2 arming
initiator which sends gas pressure to fire the M16 leg guard thruster,
MlA2 hatch jettison thruster, and M5A2 table stowage initiator. Gas
expansion from the table stowage initiator fires the M3A3 .table stowage
thruster, thus moving the table to the stowed position. Rotation of
the leg guards locks the shoulder harness inertia reel.

As the escape hatch is jettisoned, the catapult safety pin-pull M3A2
initiator is fired by means of a link attached to the escape hatch.
Gas expansion from the catapult safety pin-pull initiator operates
the safety pin-pull cylinder causing it to retract the pin that acts
as a safety on the catapult M3A2 initiator..If the catapult safety
pin-pull initiator fails to fire when the hatch is jettisoned, pulling
the safety pin-pull manual handle operates the safety pin-pull
cylinder manually.

The last part of the ejection control handle movement fires the
catapult initiator. Gas expansion from the catapult initiator fires
the M4A1 catapult and the 0.30-second delay integrated hamess
release M26 initiator. Firing of the catapult causes the seat and
the ejectable rails to move downward on the fixed rails.

As the seat ejects, the drogue parachute support arm release M27
initiator is fired by means of an initiator trip, which is mounted
on the fixed rails. Gas expansion from the drogue parachute support
arm release initiator causes the drogue parachute support arm pin-pull
cylinder to operate, thus allowing the drogue parachute support to
rotate away from the seat. As the parachute support moves away from
the seat, the drogue parachute lanyard is pulled from the drogue
parachute pack to be turned inside out by spring force resulting
in parachute deployment. The drogue parachute support rotates away
from the seat until restraint straps become taut.

Actuation of the integrated harness release pin-pull cylinder releases
the integrated hamess thus allowing the occupant to leave the seat
and it also actuates the gold key retention lock which positively
retains the gold key in a latched position. In case the integrated
hamess release pin-pull cylinder fails to actuate, there is a mechanical
backup. As the drogue parachute support rotates away from the seat,
the actuating rings attached to the boom restraint straps are pulled
from their mechanisms that mechanically release the integrated harness.
Firing of the man-seat separation actuator tightens the separation
harness and throws the occupant from the seat.